The present invention relates to drainage devices and systems and more particularly to suction drainage systems and devices for removing gases and/or liquids from medical patients, such as from the pleural cavity, by means of a pressure differential.
For many years, the standard apparatus for performing the evacuation of the pleural cavity was a drainage system known as the xe2x80x9c3-bottle set-upxe2x80x9d which includes a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient""s pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal bottle also usually prevents the back flow of air into the chest cavity.
The suction pressure (vacuum) and pressure differentials must be precisely maintained with the xe2x80x9c3-bottle set-upxe2x80x9d because of the dangerous conditions that could result if unduly high or low pressure differentials should occur. Complications such as pneumothorax may result from the loss of the water seal in the water seal bottle if suction were temporarily disconnected, and undue build-ups of positive pressure could cause tension pneumothorax and possible mediastinal shift. To accomplish this precise control, however, results in increased maintenance and monitoring. For example, evaporation in the suction control chamber or bottle results in suction pressure variations which must be corrected by the addition of more water by a nurse, doctor or other authorized medical personnel.
The 3-bottle set-up lost favor with the introduction of an underwater seal drainage system sold under the name xe2x80x9cPLEUR-EVACxe2x80x9d(copyright) in 1966 by Deknatel Inc. U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and Reissue 29,877 are directed to various aspects of the PLEUR-EVAC(copyright) system which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals and hospital laboratories. A more detailed description of the need for and the proper use of chest drainage devices is presented in the Deknatel Inc. PLEUR-EVAC(copyright) publication entitled xe2x80x9cPhysiology of the Chest and Thoracic Catheters; Chest Drainage Systems No. 1 of a series from Deknatelxe2x80x9d (1985) which is incorporated herein by reference. Among the features of the PLEUR-EVAC(copyright)) system which provide its improved performance is a single, pre-formed, self-contained unit that embodies the 3-bottle techniques. These PLEUR-EVAC(copyright) systems are sometimes referred to as wet or wetxe2x80x94wet chest drainage systems because they employ a fluid such as water both for suction control (i.e., a water manometer) and to establish the patient seal.
Despite the advantages of the PLEUR-EVAC(copyright) drainage system over the 3-bottle set-up and the general acceptance of this device in the medical community, improving the convenience and performance capabilities of chest drainage systems continues. One such improvement involved replacing the water filled manometer used for suction control with a dry or waterless suction control regulator, such as that described in U.S. Pat. Nos. 5,026,358; 5,300,050; 4,784,642 and 5,807,358. In these systems the dry suction control regulator includes a mechanism, such as a spring-loaded valve, to control the suction pressure and a water filled chamber is interposed between the suction source and the collection chamber, thereby forming the patient seal.
In these drainage devices or systems, the suction pressure actually being applied, however, could cause rapid modulation of the spring-loaded valve as a consequence of the suction pressure differentials or changes that occur during normal operation. For example, such suction pressure differentials can result from the cyclical pressure variations occurring in the suction source (e.g., suction pump). Such rapid modulation of the valve can cause the device or system to emanate a humming sound or other noise that would make the device or system unsuitable as a practical matter for the intended use (e.g. in a hospital). In order to reduce or attenuate this modulation, and thus also reduce or attenuate the unwanted sound, the drainage devices or systems are configured with a means or mechanism to dampen the rapid modulation of the valve.
In one exemplary case, such as that described in U.S. Pat. Nos. 5,026,358 and 4,784,642, attenuation of the rapid modulation of the valve in the suction control regulator is accomplished by means of a dashpot. The dashpot includes a plug that is interconnected to the plate valve member and which rides within a well. In the described embodiment, the plug is made from graphite and the well is formed of a glass annulus, which together provide non-binding surfaces so as to avoid the sticking of the component parts.
In order for the dashpot to function in the intended manner it is necessary for the plug and well to be manufactured with a high tolerance of perpendicularity. As a practical matter, this means that the plug and the member including the well must be manufactured to rather precise tolerances on the order of millionths of an inch. In addition, it is not uncommon for the plug and the member including the well to be further sorted and segregated so as to establish pairs of parts that can be used to make an acceptable dashpot, thereby minimizing wastage. Consequently, the dashpot and the components thereof are labor intensive and expensive to make.
Another type of drainage device, such as that described in U.S. Pat. Nos. 4,738,671; 4,715,856, 4,544,370; and 4,747,844, includes a modulation valve to control the suction flow, and correspondingly the suction pressure being developed, and a one way valve that forms the seal between the suction source and the collection chamber (e.g. the patient seal). These units are complex and involve a large number of parts.
It thus would be desirable to provide a waterless suction pressure regulator that includes a suction pressure control device that controls or regulates the suction pressure being applied to the waterless suction regulator. It would be particularly desirable to provide a suction pressure regulating device that would attenuate or control changes in suction pressure that could lead to rapid modulation while allowing the suction pressure regulator to be responsive to physiological induced suction pressure changes as well as long term suction source pressure changes. Such a suction pressure regulating device, and drainge devices and systems utilizing such a pressure regulating device preferably would be simple in construction and less costly than prior art devices and the methods related thereto would not require highly skilled users to utilize the device.
The present invention features a novel device, a suction pressure regulator for controlling the suction pressure being developed within the devices used for draining gases and/or liquid from the body cavity. The drainage of liquid, blood, and/or gas from the body cavity is accomplished by establishing a pressure differential between the device and the body cavity to be drained and maintaining or controlling this pressure differential at a desired value by means of the suction pressure regulator. Also featured is a pressure control regulator for use in combination with a medical device. Further featured are methods related to such a differential pressure control device and/or devices, apparatuses or systems using such differential pressure control device. Various aspects or features of the suction pressure regulator of the present invention, as well as the drainage devices using such a suction pressure regulator, provide a number of benefits as compared to prior art devices.
In a first aspect, the suction pressure regulator according to the present invention included a housing having at least one inlet aperture and at least one outlet aperture, a flexible member, a sealing member disposed with the housing and a biasing mechanism. Each of the at least one inlet aperture is in fluid communication with a pressurized gas source such as the atmosphere and the each of the at least one outlet aperture is in fluid communication with a suction source.
The flexible member extends between an outside surface of the sealing member and an inner surface of the housing so as to form a pressure boundary between the sealing member and the housing and so as to divide the interior of the housing into a first and a second compartment.
The biasing mechanism acts on the sealing member so as to selectively urge a portion of the sealing member against the housing inner surface proximal and about the at least one inlet aperture to form a seal between the at least one inlet aperture and the at least one outlet aperture, when the pressure in the housing second compartment is at or below a predetermined pressure value. Also, when the pressure in the second compartment is above a predetermined pressure value, the biasing mechanism is configured so as to allow the sealing member to move away from the housing inner surface so as to put each of the at least one inlet aperture in fluid communication with each of the at least one outlet aperture, whereby the pressurized gas source is put into fluid communication with the suction source.
Additionally, a portion of the housing that is in fluid communication with the second compartment and the suction source includes a flow regulating mechanism that restricts or controls the flow of fluid to and from the second compartment, so as to effectively control changes in pressure within the second compartment. In this way, only fluid flow to or from the second compartment that occurs for more than a given period of time can cause a change in the pressure within the second compartment. Whilst fluid flow to or from the second compartment that occurs for less than the given period or amount of time does not effectively change the pressure within the second compartment.
In particular embodiments, the flow regulating mechanism includes a porous plug, an orifice, a tortuous flow path or other means known to those skilled in the art for restricting flow, one end of which is positioned so as to be in fluid communication with the second compartment and the other end of which is positioned so as to communicate with the suction pressure source. In a more specific embodiment, the housing includes a through aperture positioned so as to be in fluid communication with the second compartment and the flow regulating mechanism comprises a porous plug that is disposed within the through aperture. The porosity of the plug is set or established so as to control the fluid flow to/from the second compartment.
In a second aspect, the biasing mechanism of the suction pressure regulator comprises a means for tensioning the sealing member closed when the pressure developed in the housing second compartment is at or below the predetermined pressure value and otherwise opening the sealing member so as to fluidly couple the pressurized gas source (e.g. ambient or atmosphere) with the suction source. Preferably, the tensioning means comprises a spring under tension and coupled at one end to the sealing member and at its other end to a support member, so as to maintain the sealing member in a closed sealing relationship with the at least one inlet aperture in accordance with the predetermined pressure value.
Also provided is means for adjusting the spring tension in predetermined preset discrete steps so as to provide one of a predetermined pressure value. Preferably, the adjusting means comprises a worm gear disposed on at least a portion of the support member; pinion gear being rotatably supported and cooperatively engaging the worm gear; dial coupled to the pinion gear and having a plurality of predetermined preset grooves along its periphery; detent member resiliently disposed against the periphery and configured and dimensioned for seating within one of the grooves and such that upon rotating the dial, the detent member rides along the periphery until seating within one of the next grooves.
The biasing mechanism according to a second aspect of the present invention further comprises means for variably calibrating the tension of the spring while the detent member is seated within one of the predetermined preset grooves of the dial so that the spring tension can be selectively varied without any rotation of the dial. In one preferred embodiment, the tension calibration means comprises a rotatable collar, the other end of the support member being secured to the collar for rotation therewith so that upon rotation of the collar together with the support member, the tension of the spring can be selectively varied while the dial is stationary. At least a portion of the dial is disposed so that the dial can be rotated externally by a user. The dial has graduations thereon to indicate the suction pressure imposed in the collection chamber while the detent member is seated in one of the grooves.
Alternatively, the biasing mechanism comprises a spring that is disposed so as to be between a lower surface of the sealing member and a lower inside surface of the housing. In this way, the spring urges the sealing member against the housing inner surface when the pressure in the housing second compartment is at or below the desired pressure value. When the pressure within the housing second compartment is greater than the desired value, the spring force is overcome causing the spring to compress and thereby allowing the sealing member to move away from the housing inner surface. The spring is preferably pre-compressed to a value corresponding to the pre-determined pressure value.
In a third aspect, there is featured a pressure control regulator that includes a housing, a sealing member moveably disposed within the housing, a flexible member and a biasing mechanism. The housing includes at least one inlet aperture and at least one outlet aperture, where each of the at least one inlet aperture is in fluid communication with a first pressure source and each of the at least one outlet aperture is in fluid communication with a second pressure source, the first pressure source being at a different pressure from the second pressure source.
The flexible member extends between an outside surface of the sealing member and an inner surface of the housing so as to form a pressure boundary therebetween and to divide an interior of the housing into first and second compartments. The biasing mechanism is responsive to pressure within the housing second compartment and acts on the sealing member so the sealing member is in one of an open position, when the pressure within the housing second compartment is greater than a predetermined pressure value, or a closed position, when the pressure therein is at or below the predetermined pressure value. In other words the biasing mechanism is responsive to the differential pressure between the housing first and second compartments.
In particular embodiments, the biasing mechanism is arranged so that in the closed position a sealing portion of the sealing member is urged against the housing inner surface so as to form a seal between each of the at least one inlet aperture and each of the at least one outlet aperture. Further, the biasing mechanism is arranged so that in the open position the sealing member is moved away from the chamber inner surface whereby each of the at least one inlet aperture is put into fluid communication with each of the at least one outlet aperture.
Also, a portion of the housing that is in fluid communication with the second pressure source, includes a mechanism to restrict the flow of fluid to or from the housing second compartment. This flow restricting mechanism restricts fluid flow such that the pressure within the housing second compartment is changed when the fluid flow in either direction occurs for a time more than a predetermined period of time and remains effectively or essentially unchanged when the flow of fluid in either direction is for a time less than the predetermined period of time. In this way, the sealing member is not responsive to fluid flow changes that are nor for more than a predetermined period of time.
Reference also should be made to the foregoing discussion for the suction pressure regulator for other aspects, arrangements or configurations of the above identified features of the pressure control regulator that correspond thereto.
In a fourth aspect, there is featured a drainage device according to the present invention for draining gases and/or liquids from a body cavity including at least two chambers, a suction pressure regulation chamber and a collection chamber that are fluidly interconnected. The collection chamber includes a port that is in fluid communication with the area or region to be drained.
The pressure regulation chamber is fluidly coupled to a source of pressurized gas, such as the atmosphere, and fluidly coupled to a suction source. The pressure regulation chamber also includes a suction pressure regulator device as described above that selectively adjusts the negative pressure or degree of vacuum being developed within the collection chamber and maintains the negative pressure or degree of vacuum being applied at or about a selected value.
More specifically the at least one inlet aperture of the suction pressure regulator is fluidly coupled to the pressurized gas source, the at least one outlet aperture, along with the housing portion in fluid communication with the second compartment, is fluidly coupled to the suction source. The biasing mechanism urges a portion of the sealing member against the housing inner surface proximal and about the at least one inlet aperture to form a seal between the at least one inlet aperture and the at least one outlet aperture, when the pressure in the housing second compartment is at or below a predetermined suction pressure value. Also, when the pressure in the second compartment is above or greater than the predetermined suction pressure value (i.e., more negative), the biasing mechanism is configured so as to allow the sealing member to move away from the housing inner surface so as to put each of the at least one inlet aperture in fluid communication with each of the at least one outlet aperture. Whereby the pressurized gas source or the atmosphere is put into fluid communication with the suction source so as to maintain the negative pressure being developed within the collection chamber at the desired value.
In a fifth aspect, the drainage device according to the present invention includes a patient seal, being interposed between the pressure regulation chamber and the collection chamber, and a venting or flow path arrangement that is interposed between the collection chamber and the patient seal. The flow path is arranged to prevent fluids accumulating in the collection chamber from being communicated upstream to other parts of the drainage device in the event that the device falls onto its front side or its backside.
In particular embodiments, the venting arrangement includes an intermediate chamber positioned proximate the backside of the drainage device and at least two flow passages. One flow passage fluidly couples the intermediate chamber and the collection chamber and another flow passage fluidly couples the intermediate chamber to the flow path going to the patient seal. In a preferred embodiment, two spaced flow passages fluidly couple the intermediate chambers and the collection chamber. These flow passages are also arranged so each is in a front-to-back type of relationship or to be essentially perpendicular to the front surface of the device.
In a sixth aspect, the patient seal of the drainage device of the present invention is configured so as to be either a wet or a dry patient seal. When configured as a wet patient seal, the drainage device further includes a third chamber, one end of which being fluidly coupled to the pressure regulation chamber and another end of which being fluidly coupled to the collection chamber. The third chamber is configured so as to include a sufficient quantity of fluid and to provide an adequate fluid level so that a fluid seal is formed and maintained at least when the suction pressure being developed in the collection chamber is at or below the desired value.
When configured as a dry patient seal, the drainage device further includes a one-way valve such as a high precision flapper type check valve. Such a valve preferably is configured so as to open at relatively low differential pressures and functions independent of any fluid collected in the collection chamber. In a particualr embodiment, the check valve opens at a pressure differential of about 0.5 cm of H2O.
Other aspects and embodiments of the invention are discussed below.